Of the world's wealthiest people, the majority still hail from the world's top economic superpower — the United States. There are 29 US billionaires who rank among the 50 richest on earth, and they command a whopping $938 billion between them.

This comes from new data provided to Business Insider by Wealth-X, a company that conducts research on the super-wealthy, featured in our recent ranking of the world's richest people. Wealth-X maintains a database of dossiers on more than 110,000 ultra-high-net-worth people, using a proprietary valuation model that takes into account each person's assets, then adjusts estimated net worth to account for currency-exchange rates, local taxes, savings rates, investment performance, and other factors.

The two richest people in America are no surprise: Bill Gates and Warren Buffett maintain their lead at the top despite being the two most generous people on earth. But US tech moguls have begun to overtake the upper echelon, with heavyweights like Jeff Bezos of Amazon and Mark Zuckerberg of Facebook adding billions to their net worth each year as their powerful companies continue to grow in value and influence.

Not everyone is an entrepreneur though. Inherited wealth has kept a hefty portion of the country's cash in the hands of a few families, as the Koch brothers, the Waltons of Walmart, and the heirs to the Mars candy conglomerate each rank among the wealthiest.

Read on to learn more about the 29 Americans with the deepest pockets.

28. James Simons

Before revolutionizing the hedge fund industry with his mathematics-based approach, "Quant King" James Simons worked as a code breaker for the US Department of Defense during the Vietnam War, but was fired after criticizing the war in the press. He chaired the math department at Stony Brook University for a decade until leaving in 1978 to start a quantitative-trading firm. That firm, now called Renaissance Technologies, has more than $65 billion in assets under management among its many funds.

Simons has always dreamed big. About 10 years ago, he announced that he was starting a fund that he claimed would be able to handle $100 billion, about 10% of all assets managed by hedge funds at the time. That fund, Renaissance Institutional Equities Fund, never quite reached his aspirations — it currently handles about $10.5 billion — but his flagship Medallion fund is among the best-performing ever: It has generated a nearly 80% annualized return before fees since its inception in 1988.

In October, Renaissance shut down a $1 billion fund — one of its smaller ones — "due to a lack of investor interest." The firm's other funds, however, have been up and climbing. Simons retired in 2009, but remains chairman of the company.

Though she's best recognized through her iconic husband, Jobs has had a career of her own. She worked on Wall Street for Merrill Lynch and Goldman Sachs before earning her MBA at Stanford in 1991, after which she married her late husband and started organic-foods company Terravera. But she's been primarily preoccupied with philanthropic ventures, with a particular focus on education. In 1997, she founded College Track, an after-school program that helps low-income students prepare for and enroll in college, and in September she committed $50 million to a new project called XQ: The Super School Project, which aims to revamp the high-school curriculum and experience.

27. Charlie Ergen

After four years away from satellite TV provider Dish Network, the company he founded in 1980, Charlie Ergen returned to his position as CEO last spring. But Ergen's reunion came amid difficult times for Dish, as the company has been striving to stem its slipping number of subscribers.

But one of the network's newest services might be its saving grace. Last January, the company launched Sling TV, a streaming service that allows subscribers to watch their favorite channels, such as ESPN and Food Network, online for only $20 per month. Though Sling is a 180-degree pivot from Dish's signature product, it has caught on with customers, inspiring copycat services and potentially providing the struggling company with the leg up it needed.

Despite not offering wireless plans to subscribers, Ergen also bought up nearly $10 billion worth of wireless-spectrum licenses at an auction last year. But the purchase incited significant backlash against Dish, which through two controlled affiliates had secured a 25% small-business discount that was subsequently revoked by the FCC. The company was forced to pay penalties exceeding $500 million to the FCC and surrender some of the licenses. Controversy surrounding Ergen's leadership is nothing new, however. His reputation for cutthroat business tactics in the past led The Hollywood Reporter to dub him the "the most hated man in Hollywood."

At the top of his industry and having amassed an enormous fortune, Dalio has more recently focused on giving away money and advice. He's taken the Giving Pledge, committing to donate the majority of his wealth to charity. And last year he shared his highly coveted "investment secrets," albeit in an unorthodox manner for a hedge funder, in a 30-minute YouTube video, which has been watched more than 2 million times. His 123-page, self-published manual on his principles of money management and leadership is also seen as somewhat of a bible among the investment world.

Dalio has always taken a radical approach to management, making everything he and his fund does completely transparent to employees. And it's worked well for him: Bridgewater, while sometimes viewed as "cultish," is one of the most coveted places to work in finance. Dalio has said that he attributes his success, in part, to reminding himself that history repeats itself and keeping track of the decisions he's made that didn't work.

25. Len Blavatnik

After earning degrees at Columbia University and Harvard Business School, Len Blavatnik — a Ukraine-born American — founded Access Industries, a privately held industrial company, in 1986. The company began with only Russian investments, but it now boasts a diverse portfolio that includes natural resources, chemicals, media and telecommunications, and real estate.

Blavatnik built his fortune through business savvy and a knack for making well-timed investments. In 2004, his company purchased a 20% stake in Tory Burch, becoming the first and largest outside investor in the fashion house, which has since blossomed into a powerhouse retailer worth over $3 billion. He's credited with one of the greatest investments of all time in his risky buyout of petrochemicals maker LyondellBasell, which he purchased out of bankruptcy amid the financial crisis for north of $2 billion. The value of his stake had jumped to more than $10 billion in 2014. He incurred a comparatively measly fine of $656,000 from the Federal Trade Commission in October for failing to properly report his investments in the company.

Recently he's tried his hand as a music mogul, purchasing Warner Music Group in 2011 for $3.3 billion. Two years later, he bought British label Parlophone for $742 million, giving him an expanded roster of musical acts that includes Coldplay, Blur, Metallica, and Bruno Mars. His music holdings also include investments in emerging-technology companies such as Spotify and Beats Electronics.

24. Donald Bren

Donald Bren, the wealthiest real-estate mogul in America, is the sole owner of The Irvine Co., a private real-estate developer with properties primarily in Orange County and along the California coast. After serving three years as an officer in the US Marine Corps, the then 26-year-old founded Bren Co. in 1958 and built his first property in Newport Beach, California, with a $10,000 bank loan.

In 1977, Bren and his business partners purchased The Irvine Co. — named for one of Orange County’s earliest developers — for $337 million. Bren held a 34% stake in the company and served as the vice chairman before buying out five stockholders, which increased his stake in the company to 86%. By 1996, he became the sole owner of the company, whose portfolio of properties — collectively known as the Irvine Master Plan — exceeds 110 million square feet and includes 500 office buildings, 41 retail centers, 130 apartment communities, three hotels, five marinas, and three golf clubs. The Irvine Co. also owns 50,000 acres of permanently preserved land in Orange County. Bren is reportedly eyeing Silicon Valley as his next venture.

Through his Donald Bren Foundation, which focuses on education and conservation, Bren has donated more than $1.3 billion to charitable causes.

23. Paul Allen

Alongside his cofounder Bill Gates, Paul Allen credits Microsoft for his fortune. Although Allen left the company before it went public in 1986, he remained a board member until 2000 and today holds a less than 5% stake. The college dropout went on to found Vulcan, his private-investment vehicle, shortly after leaving the software giant.

With lifetime donations exceeding $2 billion, Allen's philanthropic efforts make him one of the most generous people in the world. The Paul G. Allen Family Foundation gives to global health causes, including $5 million to Seattle BioMed, $4 million to Global FinPrint — a conservation project focused on the preservation of sharks worldwide — and $7 million in grants to Alzheimer's research. During West Africa's Ebola pandemic in 2014, Allen gave more than $100 million to develop solutions to stem the outbreak. In October 2015, the foundation announced seven new grants totaling $11 million to prevent future widespread Ebola outbreaks.

The self-made billionaire also counts an extravagant lineup of cars, World War II fighter jets, real estate, and two sports teams — the Seattle Seahawks and the Portland Trailblazers — among his luxurious array of assets.

22. Carl Icahn

Carl Icahn has made a lifelong habit and lucrative career out of agitating undervalued and poorly managed companies to change their ways. Since founding his own investment firm in 1968, Icahn has become one of the most powerful people in finance, investing in scores of high-profile companies, including RJR Nabisco, Philips Petroleum, Viacom, Marvel, Time Warner, Netflix, and Herbalife.

Icahn has said that he has no plans of retiring from pestering corporate executives, but a career shift may nonetheless be in the works. Donald Trump has said that if elected US president, he would bring Icahn in as Treasury secretary — a position which Icahn said he would accept despite some disagreements with the combative real-estate mogul's positions.

21. Michael Dell

While he was a premed student at the University of Texas at Austin in 1984, Michael Dell started a company called PC Ltd., the predecessor to Dell Inc., with a seed fund of $1,000. Dell soon dropped out of college to build computers full-time and found himself at the helm of one of the fastest-growing companies in the country, with $6 million in sales in its first year of business.

By the time he was 23, the company went public and raised $30 million — $18 million of it going to Dell personally. Four years later, the CEO became the youngest man to ever lead a Fortune 500 company. Aside from a brief hiatus as CEO between 2004 and 2007, Dell has been the chairman and CEO of Dell Inc. since its inception. After a furious battle with Carl Icahn, Dell took his computer company private again in 2013 in a deal valued at nearly $25 billion.

19. Sheldon Adelson

The "King of Las Vegas" first hit the jackpot in 1995 when he was 61 and running Computer Dealers' Exhibition (COMDEX), one of the largest trade shows in Las Vegas. That year, Adelsonsold the company to Japan's Softbank for $860 million and used the cash to finance his purchase of the Sands Casino. He quickly demolished it and in its place built the Venetian Casino Resort and the Sands Expo Convention Center. After further expansion, he took his gambling conglomerate, Las Vegas Sands, public in 2004.

Adelson, a former reporter and mortgage broker and the son of Ukrainian-Jewish immigrants, was hit hard during the financial crisis in 2008, reportedly losing $25 billion and needing to bolster his company's balance sheet with $1 billion of his own cash. Though the Sands had a rough 2015 — the stock tumbled 25% during the year — his fortune has recovered from the dark days of 2008 and now sits at $23 billion. He still runs the Sands and is CEO of China Sands, a subsidiary that plans to open its fifth casino in Macau this year.

The casino magnate, who owns 13 private jets, is a staunch supporter of the Republican Party, famously donating tens of millions of dollars to past candidates like Newt Gingrich and Mitt Romney. In late 2015, he purchased Nevada's largest newspaper for $140 million.

18. Phil Knight

After a stint in the US Army, and with a Stanford MBA under his belt, Phil Knight convinced Tiger-brand shoemaker Onitsuka in the early 1960s to allow him to distribute Tiger shoes under the name Blue Ribbon Sports — the name Knight picked that predated his swoosh-logo-clad company Nike. Knight worked full-time as an accountant as he launched his new brand, and by 1968 he had built up enough of a rapport with customers that he was able to leave the CPA life behind.

Nike has built its success on celebrity and athlete endorsement deals, starting with running prodigy Steve Prefontaine in 1973 and continuing with one of the most successful shoe marketers of all time in Michael Jordan, whom Nike signed to a five-year endorsement deal in 1984 worth roughly $500,000 per year. The biggest NBA star today is still under the Nike roof, with LeBron James signing a lifetime contract with the brand in December for an undisclosed sum.

Though Knight announced plans in June to step down as chairman of Nike, he's leaving the $30.6 billion (in sales) company in better shape than ever, with the stock and revenues at all-time highs.

17. Steve Ballmer

Steve Ballmer dropped out of business school at Stanford in 1980 to join Harvard friend Bill Gates at Microsoft as the company's first business manager, earning a $50,000 salary and a stake in the company. During his tenure, Ballmer held positions as vice president of marketing, vice president of systems software, and executive vice president of sales and support, and was often referred to as "the numbers guy."

He became CEO of the company in 2000 after Gates stepped down, and he remained in charge of the software giant until Satya Nadella replaced him in 2014. While running Microsoft, the company's revenue grew by 294% and profits by 181% — although its market share was surpassed by Google and Apple during the same period. Still, the early stake Ballmer acquired in the company made him immensely wealthy. He's only the second person, not including founders and their family, to ever become a billionaire from employee stock options, according to Wealth-X.

After stepping down as CEO, Ballmer fulfilled his dream of owning an NBA franchise, paying $2 billion in a deal to buy the Los Angeles Clippers, now his main venture. And last fall Ballmer revealed that he purchased a 4% stake in Twitter.

Siblings Forrest, Jacqueline, and John Mars inherited a stake in the iconic candymaker Mars Inc. when their father, Forrest Sr., died in 1999. The notoriously private trio co-own but don't actively manage the maker of M&M's and Milky Way bars, which their grandfather started in 1931 as a confectionary business in his kitchen in Tacoma, Washington.

In 2008, Mars Inc. branched out from chocolate to gum, when it acquired the Wrigley Jr. Co. for $23 billion. Since then, it's delved into pet food, buying Iams and two other brands in 2014 from Procter & Gamble for close to $2.9 billion.

Together the three siblings run the Mars Foundation, which gives primarily to educational, environmental, cultural, and health-related causes. In March 2015, John Mars was made an honorary knight by Queen Elizabeth II.

13. Alice Walton

The daughter of late Walmart founder Sam Walton, Alice Walton holds a major piece of the company fortune, making her the richest woman on earth. Though she never took an active role in running the superstore like her brothers, she's become the target of pushback from minimum-wage Walmart employees who view her highfalutin lifestyle as insensitive and ignorant to the plights of many workers.

Instead of spending time at Walmart, Walton has become a patron of the arts. Her immense personal collection includes pieces from Andy Warhol, Norman Rockwell, and Georgia O'Keefe. In 2011, she opened the $50 million Crystal Bridges Museum in Arkansas, where a number of her famous paintings are on display.

12. Rob Walton

Samuel Robson "Rob" Walton is the oldest son of Walmart founder Sam Walton. He started working at the iconic retail behemoth in 1969, holding positions from senior vice president to general counsel to chairman, a role he stepped down from in June after 23 years on the job. His son-in-law was named as his successor.

Despite Walmart's reputation as a greedy corporation that underpays its employees, the Walton family — the richest in America — has a philanthropic streak. Regulatory filings on New Year's Eve revealed that he and his brother each gave away 1.5 million Walmart shares to the family charity, Walton Family Holdings Trust, while sister Alice gave away 3.7 million shares, for a total family donation of $407 million. It's an incredible amount, but it's also ultimately a drop in the bucket for the Waltons, whose stake in the company — about 50% — is worth nearly $100 billion.

11. Jim Walton

James "Jim" Walton's parents, Helen and Sam Walton, purchased a controlling stake in Arkansas' Bank of Bentonville the year before opening the first Walmart store in Rogers, Arkansas, in 1962 — when Jim was just 14. Within five years, the family owned 24 of the retail stores and in 1972 listed Walmart on the New York Stock Exchange. In 1975, after working in Walmart's real-estate department for a few years, Jim joined his parents' bank, later renamed Arvest Bank Group. He's now chairman and CEO of the regional community bank, which has $15 billion in assets.

The businessman is also director of Walton Enterprises, the holding company for the Walton family assets, and chairman of Community Publishers, an Arkansas-based newspaper firm. After the death of his brother John in 2005, Jim joined the board of Walmart, where he serves as a director today.

While America's richest family remains incredibly private, the Walton Family Foundation, of which Jim is secretary and treasurer, has donated millions to charitable causes. In December 2015, Jim and his siblings donated $407 million worth of Walmart shares to a newly formed trust that funds the Walton's philanthropy, which focuses on educational, cultural, community development, and social causes.

10. Sergey Brin

Along with cofounder Larry Page, Sergey Brin helped facilitate Google's massive restructuring, which the company announced in August. The move put Google under the auspices of a new holding company called Alphabet, run by Brin as president and Page as CEO. Google's other ventures, such as Nest and Google X, are now separate companies also under the Alphabet umbrella. The tech giant generated $66 billion in sales in 2014, up more than $10 billion from the year before.

The restructuring allows Brin to focus on exploring inventive new "moonshot" projects and ideas. With top talent and an abundance of resources at its disposal, Alphabet has already made automated homes and self-driving cars a reality.

Brin, who emigrated from Moscow to the US as a child, connected with Page in 1995 at Stanford, where they were each pursuing a PhD. Three years later they founded Google, now one of the most powerful companies on the planet.

9. Larry Page

As a Stanford PhD student in 1998, Larry Page teamed up with classmate Sergey Brin to create BackRub, an early search engine. The project eventually morphed into Google — now called Alphabet — one of the largest and farthest-reaching companies in the world, worth more than $500 billion.

Page oversaw major changes to Google's business structure last year, starting with the creation of Alphabet, the new holding company that now manages Google and all of its related ventures, including Nest, Calico, and Google X. Previously the chief executive of Google, Page moved up to helm Alphabet, which has its hands in everything from home automation to self-driving cars to prolonging human life. In 2016, analysts expect to see a slew of acquisitions, a greater focus on mobile and the cloud, and the genesis of even more long-term "moonshot" projects.

Page doesn't make a lot of splashy purchases, but the alternative-energy advocate does own an eco-friendly mansion in Palo Alto that uses geothermal energy and rainwater capture. He's also an avid kiteboarder.

8. Michael Bloomberg

Michael Bloomberg founded his financial-data firm in 1981 following a lucrative career at investment bank Salomon Brothers, which he joined in 1966 after earning his MBA from Harvard Business School. He added a news and media subsidiary to his company in 1990, but even today the bulk of Bloomberg LP's $9 billion in revenues still comes from the sale of terminals that Wall Street traders rely on for the most up-to-date financial and market information.

He left the company to run New York City as mayor in 2002 and served three terms. But rather than spend his time after leaving office in 2013 by giving away his immense wealth, as expected, he instead returned to Bloomberg LP to overhaul the newsroom and take the company in a new direction.

Now, Bloomberg may be looking to return to public office. He is reportedly exploring the possibility of an independent presidential bid. Though he faces an uphill battle — he's a pro-business fiscal conservative who also supports gun control, abortion rights, and efforts to curb climate change — his personal war chest will come in handy. The former mayor, who spent $261 million on his campaigns for New York City office, says he'd spend as much as $1 billion of his own money on a presidential run.

7. Mark Zuckerberg

In 2004, Mark Zuckerberg, then a 19-year-old sophomore at Harvard, launched TheFacebook.com, a rudimentary version of the now ubiquitous social network known as Facebook. Zuckerberg dropped out of college to work full-time as Facebook's CEO, and the site quickly exploded in popularity. Today, it attracts more than a billion users daily and is worth more than $275 billion, hittingall-time stock highs in November after beating earnings expectations. At 31, Zuckerberg is by far the youngest of the 50 richest people in the world.

Zuckerberg and his wife, Priscilla Chan, welcomed a daughter, Max, into the world in November, and Zuck took two months off from work to spend time with her, setting an example of Facebook's strong paternity-leave policy.

The pair also pledged in December to give away 99% of their wealth in their lifetimes through a new organization called the Chan Zuckerberg Initiative, though some critics noted this new organization wasn't a nonprofit charity itself and found the announcement misleading. But this isn't the couple's first foray into philanthropy. They donated $25 million in the fight against Ebola last year, and they gave $100 million worth of Facebook shares toward improving a New Jersey public-school system.

6. Larry Ellison

In 1977, Larry Ellison teamed up with two colleagues from an electronics company to start their own programming firm, which landed a contract not long after to build a relational database-management system for the CIA under the project code Oracle. The project grew into what is known today as Oracle Corp., the second-largest software maker behind Microsoft. In 2010, Ellison reduced his annual salary from $1 million to $1, but he still takes in more than $60 million in total compensation thanks to generous stock awards. Ellison stepped down as CEO in 2014 after 38 years on the job and took on the role of chief technology officer.

Included in Ellison's $45 billion fortune is an expansive global real-estate portfolio that features an entire Hawaiian resort island and an accompanying airline that he's rumored to be selling. He's a tennis fan — his current passion project is to revive the sport through investments in a "fifth grand slam" site in Indian Wells, California, and as lead sponsor for the Intercollegiate Tennis Association.

The tech tycoon is also a generous philanthropist through partnerships with wildlife conservation groups and the Lawrence Ellison Foundation, which supports organizations that research aging and global infectious diseases. He's also a member of Bill Gates and Warren Buffett's Giving Pledge, committing to give away at least half of his fortune.

5. Charles Koch

Charles Koch is chairman and CEO of multifaceted conglomerate Koch Industries, the second-largest private company in America. His younger brother David is the executive vice president. The company employs 100,000 people and generates $115 billion in sales from its diverse company, which makes everything from petrochemicals and Dixie Cups to raw clothing materials.

Outspoken in the world of conservative politics, the Koch brothers, who have a combined net worth of $94.2 billion, wield a heavy influence over the upcoming 2016 US presidential race. The two at one point favored Republican candidate and former HP CEO Carly Fiorina, but have since said that they won't support any of the current candidates in the primary. But they, along with their vast donor network, plan on pitching in some $750 million during the 2016 election cycle.

Recently surfaced documents revealed that Charles Koch's plans to reshape American politics date back 40 years, when he began strategizing and developing a libertarian movement.

Famously conservative, the brothers also maintain immense political influence and pledged to spend, along with their vast donor network,some $750 million on 2016 campaigns and causes. David tends to stay out of the spotlight more than his brother Charles, who announced in November that the brothers would not be backing any of the current GOP candidates in the primaries, a sign that they aren't confident in the state of the party.

David has had two brushes with death. He survived a plane crash in 1991 in which everyone else in first class died, and he also won a battle with prostate cancer. He's become one of the world's most generous givers since, pledging to contribute more than $1.2 billion to cancer research, hospitals, education, and cultural institutions over his lifetime through his David H. Koch Charitable Foundation.

3. Jeff Bezos

Jeff Bezos earned his massive fortune by introducing e-commerce to the world. After spending time in finance on Wall Street, Bezos founded Amazon.com in the garage of his Seattle home in 1994 and operated it exclusively as an online book retailer. The company went public three years later and has since grown to include everything from furniture to food to Amazon's own consumer-electronics products, generating $89 billion in sales in 2014.

While Bezos, chairman and CEO, faced a barrage of negative media attention last year for reports that Amazon's warehouses are high-pressure, toxic work environments — claims he disputed — the internet retailer continues to thrive with the growth of Amazon Web Services, the company's cloud-computing branch, and a bold plan to conquer India's "trillion dollar" online-retail market.

Bezos also has interests outside of Amazon, including investments in his privately owned space company Blue Origin, which successfully launched its first spacecraft in 2015, and The Washington Post, the newspaper he bought in 2013. And early this month he invested millions in a company that's creating a simple blood test to detect every form of cancer.

2. Warren Buffett

Berkshire Hathaway CEO Warren Buffett started his prodigious investing career at a young age. As a child he delivered newspapers on his bike, and by 11 the precocious Nebraska native had purchased his first shares in the stock market — Cities Service Preferred at $38 apiece — and sold them for a $5 profit. He was rejected from Harvard Business School, so Buffett went to Columbia Business School instead and learned under iconic value investor Benjamin Graham, who would become a mentor to the budding financier. Buffett worked as a securities analyst in the early-1950s before starting his own investment firm. He bought textile company Berkshire Hathaway in 1969, transforming it into a holding company that would house the many lucrative investments that helped build his massive fortune and earn the nickname "The Oracle of Omaha."

The array of portfolio companies and investments that made him rich may appear random — he's bet on companies including Coca-Cola, American Express, Geico, Fruit of the Loom, Dairy Queen, and General Motors — but they're all cash-generating machines that offer long-term value. In August he announced his largest acquisition ever: a $37.2 billion buyout of nuts and bolts maker Precision Castparts.

1. Bill Gates

At just 20, Bill Gates cofounded Microsoft with his childhood friend Paul Allen. Months before his 31st birthday, the company went public, making Gates a billionaire. He served as CEO of the software titan until 2000 and was its chairman and largest shareholder until 2014. Though he still sits on the company's board, Gates — whose net worth sits a league above the rest at $87.4 billion — is no longer actively involved in Microsoft.

Gates is not only the richest man in the world, but he's also the most generous. Since 1999, Gates and his wife have helmed the Bill & Melinda Gates Foundation, one of the most powerful charities in the world. The foundation — which controls an endowment of more than $40 billion — aims to lift millions of people out of poverty, with a heavy focus on eliminating HIV, malaria, and other infectious diseases. The couple is also working on a plan to bring mobile banking to the 2 billion adults who don't have a bank account. Plus, Gates recently invested alongside Jeff Bezos in Grail, the company that's creating a blood test to detect every form of cancer.

He's also cofounder of the Giving Pledge, which he launched in 2010 with good friend and fellow billionaire Warren Buffett as a promise to donate 50% or more of their fortunes. The Giving Pledge now counts Mark Zuckerberg and Elon Musk among its 137 members.